It has been well known in the art of power supplies for high speed computers to use a switching regulated power supply to convert power from a standard 110 volt alternating current to a precise low voltage, high direct current. Typically, such low voltages are 2 volts, 5 volts, 12 volts, or 15 volts and currents ranging up to 200 amps. As used in this specification, the term "switching power supply" refers to that general class of power supplies in which an alternating current source at one frequency, typically 60 Hertz, is converted to a regulated alternating current source at a much higher frequency, typically 20,000 Hertz. This high frequency voltage is stepped down in an output stage and the output rectified to a smooth direct current at the lower voltage.
Switching regulated power supplies are generally used to supply the bias voltage for digital computer solid state logic elements. These logic elements in the computer are typically transistor integrated circuit stages, which change state or switch in response to either a logic impulse from another logic element or in response to a transient signal having a voltage in excess of the switching threshold voltage of the transistor. Such accidental transients will cause a switching of the logic elements of the computer which will upset the operation and control of the logic elements. Such an occurrence could result in either a minor error in the operation of the computer or could result in a complete upset and breakdown of the operation of the computer. Thus, it is seen that if a power supply having a direct current output which contains ripples or transients or other noise is used as a power supply for a computer, the transients, ripples, or noise in the power will be transmitted to the logic elements and can cause the undesirable upset of the logic elements in the computer. Therefore, computer power supplies must have an extremely smooth direct current output completely free of transients or ripples which could cause logic breakdown in the computer. For this reason, power supplies having a smoother direct current output free of ripple or noise have been sought after in the art.
Miniaturization has long been a goal in the art of computer packaging. For this reason, the space restrictions for the associated power supplies for a computer have become increasingly stringent, creating a necessity for decreasing the size of power supplies used on computers.
Competition in the marketing of computers has led to a desire for computers with enhanced capabilities, requiring a greater number of logic elements. Such an increase in the number of logic elements increases the power required to run the computer having the enhanced capabilities. Thus, ways to increase the power capabilities of the power supply of a computer without necessitating an increase in the size of the power supply have been sought after.
Power supplies of the prior art have typically been plagued with two problems. First, the direct current output of such power supplies often has ripple or noise due to the long distances between output voltage buses. Secondly, such power supplies have been plagued by inefficient power output due to resistance losses caused by the long or non-uniform distances of electrical path lengths within the power supply.